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To examined alkaline phosphatase enzyme (ALP) activity and the effects of incorporating it in the thickener solution of a hydrogen-peroxide-based bleaching gel containing calcium-polyphosphate (CaPP) on the orthophosphate (PO43−) levels, bleaching effectiveness, and enamel microhardness. ALP activity was assessed at different pH levels and H2O2 concentrations, and in H2O- and Tris-based thickeners. Circular dichroism (CD) was used to examine the ALP secondary structure in water-, Tris-, or H2O2-based mediums. The PO43− levels were evaluated in thickeners with and without ALP. Enamel/dentin specimens were allocated into the following groups: control (without bleaching); commercial (Whiteness-HP-Maxx); Exp-H (H2O-based); CaPP-H; ALP-H (CaPP+ALP); Exp-T (Tris-based); CaPP-T; and ALP-T (CaPP+ALP). Color changes (ΔE/ΔE00) and the bleaching index (ΔWID) were calculated, and surface (SMH) and cross-sectional microhardness (CSMH) were assessed. The two-way ANOVA and Tukey's post-hoc tests were used to compare ALP and PO43− levels; generalized linear models were used to examine: ΔE/ΔE00/SMH/CSMH; and Kruskal–Wallis and Dunn's tests were used for ΔWID (α = 5%). The ALP activity was higher at pH 9, lower in H2O2-based mediums, and similar in both thickeners. The CD-spectra indicated denaturation of the enzyme upon contact with H2O2. The PO43− levels were higher after incorporating ALP, and the ΔE/ΔE00/ΔWID were comparable among bleached groups. SMH was lower after bleaching in Exp-H, while CSMH was highest in ALP-T. [ABSTRACT FROM AUTHOR]

Objective: To assessed in vitro the effect of nanohydroxyapatite (n‐HA) to improve the aesthetic appearance and microhardness of white spot lesions (WSL) when associated with a low‐concentration bleaching agent (carbamide peroxide—CP10%). Material and methods: Enamel/dentin specimens (n = 60) of 5 × 5 × 2.2 mm were prepared, of these, 48 were submitted to pH‐cycling to create artificial WSL. Subsequently, these were allocated into five groups (n = 12): n‐HA; n‐HA + CP10%; CP10%; WSL control (WSLC); sound control (Sound). The color was assessed at baseline, pre‐treatment, and post‐treatment using a spectrophotometer, and the color (ΔE/ΔE00) and whiteness index (ΔWID) alterations were determined. The enamel cross‐sectional microhardness (CSMH) was evaluated (post‐treatment) with a Knoop indenter, 25gf/5 s, 20–200 μm. The data was analyzed through generalized linear models (α = 5%). Results: ΔE and ΔE00 were significantly higher for the bleached groups (n‐HA + CP10% and CP10%), and the n‐HA was higher than the WSLC group (p < 0.05). ΔWID was significantly higher for the bleached groups (p < 0.05). The CSMH values were significantly higher in the sound group than in the n‐HA, CP10%, and WSLC groups (p < 0.05). The WSLC had lower microhardness than the n‐HA + CP10% and sound groups (p < 0.05). Conclusion: n‐HA is suitable to remineralize and recover the color of the WSL. However, its association with CP10% maintains the esthetical outcome while increasing its in‐depth remineralizing effect. Clinical significance: Considering the aesthetic and functional repercussions of the WSL persistence, treatments that tend to improve its physical appearance and reinforce its weakened substructure in a non‐invasive way are ideal. For this associating low‐concentration, bleaching agents to the remineralizing treatments is promising to treat this type of lesions. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of nanohydroxyapatite (nHAP) associated with photobiomodulation (PBM) in the control of dentin hypersensitivity (DH). Methods: 32 subjects with 83 hypersensitive teeth were randomized into four groups (N =8): GPlacebo - simulated PBM (without light emission) followed by the application of nHAP-free toothpaste; GLaser - PBM followed by the application of nHAP-free toothpaste; GnHAP - simulated PBM followed by the application of nHAP; GLasemHAP - PBM followed by the application of nHAP. A visual analogue scale (VAS) was used to measure DH after a tactile and evaporative stimulus. DH evaluations were performed at four times: baseline, 1st, and 2nd treatment sessions, and 1 month. A questionnaire was used to evaluate the risk factors associated with DH intensity. Mixed-design ANOVA followed by Tukey test and logistic regression were used. Results: The mechanical stimulus showed a significant reduction in DH in all experimental groups (P< 0.05) at the 2nd treatment session. For the evaporative stimulus, the GLasemHAP group presented a significant reduction in DH at the 1st treatment session (P< 0.05). Intragroup analysis showed that only the GnHAP group showed regression of DH at 1 month for the two applied stimuli. The variables of parafunctional habits, diets rich in acidic drinks and anxiety had significant relationships with the intensity of DH (P< 0.05). [ABSTRACT FROM AUTHOR]

Purpose: To analyze the current evidence on the impact of surface finishing protocols (such as manual polishing or glazing) on the color stability of in vitro simulated pigmentation of CAD/CAM ceramics., Materials and Methods: Five electronic databases were searched on February 12, 2020. In vitro experimental studies were included based on the following strategy: intervention = surface treatment of CAD/CAM ceramics with glazing agents; comparison = surface treatment of CAD/CAM ceramics with manual polishing; and outcomes = color stability. Two reviewers independently assessed the risk of bias., Results: Among 1,390 articles that were screened, 6 in vitro studies were considered for qualitative analysis. Five articles confirmed changes in the color of ceramics when they were immersed in pigmented solutions. One article investigated the color stability of the samples via ultraviolet (UV) aging. Among the 6 studies analyzed, 4 showed clinically acceptable color alteration values represented by ΔE irrespective of the finishing protocol applied (glazing or mechanical polishing). Two articles presented clinically unsatisfactory color variation (ΔE > 3.3 and ΔE > 2.7) following mechanical polishing of a zirconia-reinforced lithium silicate ceramic. Coffee and red wine proved to be the beverages with the greatest potential for ceramic pigmentation. Only 1 article had a high risk of bias., Conclusion: For clinicians, most of the studies demonstrated that both manual polishing and glaze application can prevent significant color alterations on CAD/CAM ceramic surfaces. However, due to the relatively limited amount of evidence to support this conclusion, further studies must be conducted.